This paper reports on a study that examines the effect of
shoulder belt load limiters and pretensioners as well as crash and
occupant factors that influence upper torso harm in real-world
frontal crashes. Cases from the University of Michigan
International Center for Automotive Medicine (ICAM) database were
analyzed. Additional information was used from other databases
including the National Highway Traffic Safety Administration
(NHTSA) New Car Assessment Program (NCAP), the Insurance Institute
for Highway Safety (IIHS), the National Automotive Sampling System
- Crashworthiness Data System (NASS-CDS), and patient data
available from the University of Michigan Trauma Center. The ICAM
database is comprised of information from real-world crashes in
which occupants were seriously injured and required treatment at a
Level 1 Trauma Center. Cases from the database were included in
this study if they met the following criteria: (a) the primary
collision involved a frontal type crash and; (b) case occupants
were seated in front outboard positions, restrained by 3-point
safety belts and deployed frontal airbags.
One hundred thirty-three (133) case occupants who sustained
nearly 1,800 injuries were selected for study from the ICAM
database. The study included evaluations of skeletal, organ, and
vessel injuries to the upper torso. Potential influencing factors
were divided into three general categories: vehicle factors (i.e.,
seatbelt design); occupant factors; and crash related factors.
Considering the challenges and limitations for analysis of field
accident data and within the scope of this study, data indicated
that: case occupants without shoulder belt load limiters
experienced a higher level of upper torso harm in lower severity
frontal crashes. The average Delta V for case occupants with
shoulder belt load limiters was significantly higher (7.1 km/h, 34%
greater crash energy) than that for the case occupants without load
limiters. Case occupants with shoulder belt load limiters had
significantly fewer clavicle fractures in frontal crashes. For the
62 case occupants with load limiters, the presence or absence of
pretensioners did not appear to substantially change the crash
severity associated with AIS ≥2 upper torso harm. Lower bone
mineral density of the L4 vertebra was indicative of susceptibility
to upper torso skeletal injuries. Smaller psoas muscle cross
section area was indicative of susceptibility to upper torso
internal and skeletal injuries.